PHOENIX — Blue Cross Blue Shield of Arizona decided Wednesday to maintain its presence in Pinal County in offering marketplace insurance plans, sparing it the prospect of being the only place in the nation without an exchange under President Barack Obama’s health care overhaul.

Blue Cross Blue Shield had been considering pulling out of the county amid rising costs — something other insurers had already done.

Jeff Stelnik, senior vice president of sales, strategy and marketing for Blue Cross Blue Shield of Arizona, told The Associated Press the company still has concerns about the financial viability of the exchanges but felt it was necessary to give Pinal County residents a marketplace insurance option.

Stelnik said rates will increase by 51 percent in 2017 in the county, but he noted most of that will be offset by new subsidies available to Arizona residents next year.

Between 8,000 and 10,000 Pinal County residents receive health insurance through the exchanges.

“We were concerned about not only the long-term stability, but at the same time extremely concerned that Pinal residents had no options under the exchange,” Stelnik said.

The Arizona Department of Insurance didn’t immediately return a call seeking comment Wednesday.

Blue Cross announced early this summer it would not offer plans in Pinal County next year.

U.S. Rep. Ann Kirkpatrick, D-Arizona, wrote a letter last month to Blue Cross Blue Shield of Arizona’s president and CEO Rich Boals, urging the insurer to reconsider its decision.

With the exit from Arizona of UnitedHealthcare, only Aetna planned to offer plans in 2017. Early last month, Aetna also pulled out, leaving the county south of Phoenix without an exchange provider.

Blue Cross was the only insurer able to easily return to the county because it currently sells plans there.

The dilemma in Pinal County is an extreme example of what is happening around the country. Companies are citing losses on the exchanges because older, sicker-than-expected people are signing up for insurance, and not enough young and healthy people are buying coverage.

About 1 million people remain uninsured in Arizona, and young and healthy residents make up a large part of that segment. They pay a penalty for not having insurance when they file their taxes.

The problem has attracted attention in Washington.

U.S. Sen. John McCain, R-Arizona, introduced legislation that would exempt people from the penalty if they live in a county with one or no health insurance providers under the exchange.

McCain said Arizonans shouldn’t have to pay penalties because of the “failure” of a system “that was fatally flawed from the beginning.”

More than 12 million people nationwide get insurance from the marketplace. The coming year will be the fourth for the markets, and each year has seen dramatic shifts in Arizona’s plans and premiums.

Blue Cross Blue Shield has lost between $225 million and $250 million over the first three years of the exchanges, Stelnik said.

“Regulators and policy makers must find a way to stabilize the market and put long-term fixes in place,” Boals said. “In the meantime, (Blue Cross Blue Shield of Arizona) is trying hard to balance the company’s financial losses from the (Affordable Care Act) with the very real concerns of Arizonans.”